The primary task of a TCS is to ensure the stability and steerability of the vehicle when starting off and accelerating, as well as to assist the driver when driving on a slippery road surface. To this end, the slipping wheels are braked by a braking intervention if a slip threshold is exceeded, and the engine torque is adapted to the particular drive torque that can be transferred to the road.
It is known to reduce the slip thresholds for the drive wheels on the inside and outside of a curve when cornering on a road surface having a low adhesive friction value in order to adequately preserve lateral stability. However, in order for adequate propulsion to be generated in less critical curves as well, the reduction of the slip thresholds is limited.
The consequence of setting slip thresholds in this manner is that due to the relatively high allowable slip on the drive wheel on the outside of the curve in particular, the maximum possible lateral stability is not achieved, and the vehicle stability cannot be adequately improved.
Due to dynamic wheel load transfer (the wheel on the inside of the curve is relieved of load and the wheel on the outside of the curve is dynamically loaded when cornering), the drive wheel on the inside of the curve generally starts to slip first even with low lateral acceleration, and the braking intervention not only brings about the elimination of slip on the wheel on the inside of the curve but also transfers a specific torque (blocking torque) to the wheel on the outside of the curve. The effect of this blocking torque is that the slip on the wheel on the outside of the curve is once more increased “subtly” (i.e., with low dynamics), and thus the lateral stability is additionally reduced. The wheel on the outside of the curve thus continues to be underbraked and slips for a disproportionately long time, and therefore achieves only a fraction of the maximum possible lateral stability.